1. Field of the Invention
This invention relates to a dispensing assembly that includes a side-by-side pair of tubes for storing initially separate components. During a dispensing operation, the tubes are collapsed to direct the components through a static mixer where the components are mixed for application directly to a work site.
2. Description of the Related Art
A variety of materials are made of two or more initially separate components that are preferably not mixed until immediately prior to use. Examples of such materials include epoxy adhesives, sealants and coatings used in the construction industry, and dental materials such as dental restoratives, adhesives and impressioning materials. In many instances, such two-component materials may unduly cure, harden or become otherwise unsatisfactory for use if mixed too far in advance of the actual time that the material is applied to the work site.
U.S. Pat. No. 4,538,920, assigned to the assignee of the present invention, describes a dispensing device for mixing and dispensing material made of two initially separate components. The device described in U.S. Pat. No. 4,538,920 includes a syringe having side-by-side parallel internal chambers and a pair of plungers to force the contents of the chambers through respective outlet passages and subsequently through a static mixing element carried within an exit conduit. The static mixing element intimately mixes the components to form a homogeneous mass that rapidly polymerizes following expulsion from an outlet of the exit conduit.
A double-barreled epoxy injection gun is described in U.S. Pat. Nos. 5,184,757 and 5,161,715 and includes separate barrels that each receive a sausage-shaped foil pack containing one component of a two-component mixture. The gun described in U.S. Pat. Nos. 5,184,757 and 5,161,715 includes a piston in each barrel, and the piston is advanced to crush the foil packs and thereby extrude the components.
U.S. Pat. No. 3,323,682 describes a cartridge for a single-barrel gun-type dispenser, and the cartridge has an outer shell containing a side-by-side pair of semi-cylindrical tubes. The tubes are made of a flexible material such as a plastic film, and include spouts that dispense components in two, spaced apart streams as the tubes are collapsed. The cartridge shown in U.S. Pat. No. 3,323,682 includes a rear plug that slides along the inner surface of the shell and bears against the collapsible tubes to expel the components.